1. Field of the Invention
The present invention relates to an illuminated pushbutton switch, a plurality of which are arranged in a line on the front side of, for example, an automatic ticket machine to be used in a railway station, for example, so that it may be switched to vend railway tickets.
2. Discussion of the Related Art
FIG. 7 shows one of the illuminated push-button switches of the prior art, which is furnished with an indicator function to indicate a switched input signal and a piece of input information. In FIG. 7, in the top of a box-shaped housing formed by the combination of a switch case 71 and a switch base 72, there is fitted a push button 73 that protrudes from the switch case and can be pushed. The push button 73 depresses, when pushed, the actuator 76 of switch 75 through a depression member 74 which is associated with the movement of the push button 73. Then, the switch 75 is turned on, and this ON signal is indicated through illumination of an indicator 77. In FIG. 7, reference numerals 78 and 79 designate an input/output wiring flexible substrate and a return spring for the depression member 74, respectively.
In this structure, the depression member 74 interposed between the upper push button 73 and the lower switch 75 is biased upwardly by the return spring 79 to contact the upper push button 73. This structure causes the return spring 79 to rock, while being extended or contracted, and vibrates the mating portions of the push button 73 and the depression member 74. This vibration often inhibits the smooth depression of the push button 73. In the worst case, the switch 75 fails to operate when the push button 73 is obliquely pushed.
The structure also suffers from low reliability. In addition, it is impossible to reliably attain the operational feel or confirmation when the switch 75 is turned on or off, even if the depression member 74 is depressed against the biasing force of the return spring 79.
Moreover, the switch case 71 is formed with several fitting holes (although not shown) for assembling the switch components. This structure suffers from another problem in that external dust or interfering light often enters the switch case 71 via those fitting holes to degrade the switching performance.